Conversion of hydrocarbon oils



Aug. 6,1940. SEGUY 2,210,265 I I CONVERSION OF HYDROCARBON OILS FiledAug; 31, 1939 SEPARATING 8. FRMTIONA FRACTIONATOR COLUMN FURNACE 2FURNACE 68 SEPARATING CHAMBER ji DISTILLING FURNACE RECEIVER 3(5) 'IJ 79INVENTOR JEAN DELATTRE SEGUY' ATTORNEY Patented Aug. 6, 1 940 UNITEDSTATES PATENT OFFICE 2,210,265 v f v CONVERSION OF HYDROCARBON OILS JeanDelattre Seguy, Chicago, Ill., assignor to- Universal Oil ProductsCompany, Chicago, IlL, acorporation of Delaware a r Application August31', 1939, Serial No. 292,881

4 Claims. (01.196 49) This invention relates specifically to an improvedcracking system involving a combination of interdependent stepscomprising vapor-phase cracking, reforming and flash distillation whichcooperate to produce, from the charging oil and intermediate products ofthe process, high yields of good antiknock gasoline and minor yields ofgood quality liquid residue and gases.

various steps of the process are combined in an One specific embodimentof the invention comprises cracking, in essentially vaporous state, acondensate resulting, as hereinafter described, from fractionation ofrelatively clean vaporous products of the process, comminglingthe'resulting products with hydrocarbon oil charging stock and withother conversion products of the process, derived as hereinafterdescribed, and, separat ingthe mixture into saidrelatively clean vaporsand heavier liquid fractions, fractionating said relatively clean vaporsto condense therefrom,

as said condensate supplied to the vapor-phase cracking operation,components which contain no substantial quantity of gasoline fractionsand lated to produce therefrom high yields of full boiling rangegasoline of improved antiknock value, separating the products ofthevreforming I v p H a version products aredirected from coil [throughoperation into liquid and vaporous fractions, separately fractionatingthe latter to condense therefrom as reflux condensate components boilingabove the range of said gasoline of improved antiknock value, supplyingsaid reflux condensate to the same separating zone to which saidcharging stock and con-version products of the vaporphase crackingoperation are supplied, subjecting fractionated vapors resulting fromthe last described fractionating step to condensation to form gasolinewhich is recovered and; separated from the uncondensed gases, supplyingsaid liquid fractions derived from the first mentioned separating zoneand from the separating zone to which said reformed products aresuppliedto a reduced pressure distilling zone and therein effectingtheir appreciable further vaporization,

supplying a portion of said uncondensed gases to said distilling zone toassist said distillation, recovering the resulting unvaporized residualliquid, separately cracking the vapors evolved'in said distilling zonein the'presence of said uncondensed gasessupplied thereto and supplyingthe resulting conversionproducts to the same separating zone to'whichsaid charging stock, said conversionproducts of the vapor-phasecracking step andv said reflux condensate are supplied.

It will be apparent from the above that the contemplates a processinvolving less than the entire combination of steps above recited, asthere are several suchlesser combinations which involve novel andadvantageous departures from the prior artand are, therefore, within thescope of the broader aspectsof the invention.

Theaccompanying drawing is essentially a flow diagram of ,a systemincorporating the combinae tion of cooperative stepsprovided bytheinventionand in which the above outlined process, as well asv variousmodifications thereof involving less than the entire combination, may beconducted.

Referring to the drawing, the vapor-phase cracking coil l, to which issupplied a clean condensatej of relatively low end-boiling point (say600 to 650 F.) is disposed in furnace 2 and the oil supplied, as will'belater described, to this coil is substantially completelyvaporizedtherein andheated'during its passage. therethro-ugh to the desiredcracking temperature. a The resulting conline 3 and valved into'separating and fractionating column 5 andipreferably are cooled prior totheir introduction into the latter zone sufficiently'to preventsubstantial further cracking thereof. ,In the casehere illustrated, thiscooling is accomplished by directly commingling suitable cooling fluidwith the conversion products passing throughline 3 and may be assisted,when desired, by pressure reduction as the-products pass throughvalve'4in' this line.

I may'e'mploy a portion or all of the hydrocarbon oil charging stock-forthe process ascooling material in, line 3 by directing the same frompump 8, to whichthe charging stock is'supplied through line 6 andvalve], through line9, line l0 andvalve ll into line 3 and, whendesired, reflux condensate recovered from the vaporous products of-..thereforming operation hereinafter described may be commingled, all or. inpart, with or without prior cooling, with the vapor-phase conversionproducts being supplied to the column 5 to serve as cooling material forthe latter. The provisions for accomplishing cooling by the lattermethod will be later described.

The charging stock for the process may be any desired type ofhydrocarbon oil ranging from light distillate to crude petroleum,reduced crude or the like and any portion of the charging'stock notcommingled with the conversion products prior to their introduction intocolumn 5 may be supplied directly to the latter zone at any desiredpoint therein, whereby it is also commingled with the conversionproducts and assists cooling and fractionation of the latter. Line I2,controlled by valve 13 and communicating with line 9 and column 5, isprovided in the case here illustrated for introducing all or anydesiredportion of the charging oil into the latter zone.

Conversion products of a third cracking step are also supplied to column.5, as will be later described, and the commingled materials supplied tothis zone are separated therein into a relatively clean vaporous stream,having an endboiling point of the order of 600 to 650 F, for example,and heavier liquid fractions. The latter are directed from this zonethrough line I4 and valve [5 to distilling chamber I6 and the relativelyclean vapors are directed from column 5 through line H and valve I 8 tofractionation in fractionator l9.

The vapor supplied to fractionator l9 are partially condensed therein toform the clean condensate supplied as cracking stock to coil l and theremaining lighter vapors are further fractionated in this zone toform alighter condensate consisting essentially of heavy gasoline fractions,leaving a fractionated vaporous product which consists essentiallyoflight gasoline fractions of good antiknock value andgases.

The vapor-phase cracking stock is directed from fractionator l9 throughline 20 and valve 2| to pump 22 by means of which it is supplied throughline 23 and valve 24 to vapor-phase cracking treatment, in the mannerabove described, in'coil I. y

The lighter condensate formed in fractionator I9 is directed therefromthrough line 25 and valve 25 to pump 21 by means of which it is suppliedthrough line 28 and valve 29 to reforming treatmentin heating coil 30,wherein it is heated to a high cracking temperature at substantialsuperatmospheric pressure by means of heat supplied from furnace 3!,wherein coil 30 is disposed, The cracking conditions employed in coil 30are regulated to effect reforming of the heavy gasoline fractionssupplied thereto (i. e., their conversion into'high yields of gasolineof lower initial boiling point and improved antiknock value) Thereformed products are directed from coil 30 through line 32 and valve 33into separating chamber 34 and preferably are cooled prior to theirintroduction into the latter zone sufficiently to prevent theirappreciable further cracking and deleterious secondary reactions. Thiscooling may be accomplished inany well known manner and, in the casehere illustrated, provision is made for introducing suitable cooling oilinto line 32ythrough line 35 and valve 35'. Regulated quantities of the.vapor-phase cracking stock from fractionator l9 may, when desired,'beemployed as cooling oil in line 32, this material preferably beingremoved. fromline 23 and cooled to the desired temperature in any wellknown manner, not illustrated, prior to its introduction into line 32.Provision is also made for utilizing a regulated portion or all of thecharging oil to cool the reformed products from coil 30. This isaccomplished in the case here illustrated by directing charging oil fromline 9 through line 86 and valve 81 into line 32.

Chamber 34 is preferably operated at a substantially reduced pressurerelative to that employed at the outlet of coil 30. This reduction inpressure assists cooling of the reformed products and is accomplished asthe latter pass through valve 33 in line 32.

In chamber 34 separation is effected between vaporous and heavy liquidcomponents of the commingled reformed products and cooling oil, theliquid components being supplied from this zone through line 36 andvalve 31 to distilling chamber [6, while the vapors are directed fromchamber 34 through line 38 and valve 39 to fractionation in fractionator40 wherein their components boiling above the range of the desiredgasoline product of the process are condensed as reflux condensate.

The reflux condensate formed in fractionator '40 is directed therefromthrough line 4| and valve 42 to pump 43 by means of which it is fedthrough line 44 and maybe supplied therefrom, all or in part, throughline 45 and valve 46 into line 3 and thence to column 5 or a regulatedportion or all of this material may be directed from line 44 throughline 41, valve 48 and line 43 into column 5, after commingling in line49 with relatively hot conversion products of the third cracking step ofthe system, which will be later described. It is also within the scopeof the. invention to supply all or any desired portion of the refluxcondensate formed in fractionator 40 from line 45 through line 50 andvalve 5| directly to column 5 without first commingling the same withother conversion products. In order that the reflux condensate fromfractionator 40 may function efficiently as a cooling medium in the zoneor zones to which it is supplied, it may, when desired, first be passedthrough cooler 52 and therein cooled to the desired temperature, thisbeing accomplished by closing valve 53 in line 44 and opening valves 55and 51 in the respective lines 54 and 56 which connect cooler 52 withline 44.

When desired, instead of separating heavy liquid fractions from vaporsin chamber 34 the total reformed products from coil 30 and the coolingoil commingled therewith may be supplied directly to fractionator 40, bywell known means not illustrated, whereby all the components ofthese-materials boiling above the range of the desired gasoline areincluded in the reflux condensate formed infractionator 40, the heavyliquids being subsequently separated therefrom in chamber 5. a

The liquid conversion products supplied to chamber l6 from chamber 34 orchamber 5 or both, as the case may be, are appreciably further vaporizedin this zone to form a heavier residual liquid product and evolvevaporous fractions suitable for further'cracking "treatment. Chamber l6may be operated at asubstantially reduced pressure relative to thatemployed in chamber 5 and/or in chamber 33 to assist vaporization inthis zone and, in the preferred embodiment'of the invention,vaporization in chamber I6 is also assisted by the introductiontheretoof normally gaseous products of the process, as will-be laterdescribed. The residual liquidformed in'chamher It is directed therefromthrough line 60 and valve GI to cooling and storage or elsewhere, asdesired,'and the vapors evolved'in chamber I6, including any normallygaseous fractions supplied to this zone, are directed therefrom throughline 62 and'valve 63 to pump or compressor 64 wherefrom they aresupplied through line 65 and valve 66 to further cracking treatment inheating coil 61.

' Coil 61 is disposed in furnace 68, the vapors or mixture of vapors andgases passing therethrough being heated to the desired crackingtemperature, preferably at a pressure at least as high as that employedin column 5. When substantial quantities of normally gaseous fractionsare included in the materials supplied to coil 61, the conditionsemployed in the latter zone may be regulated to eifect conversion of thegases, as Well as the normally liquid fractions, into sub stantialadditional yields of gasoline.

The products formed in coil 61 are directed therefrom through line 69,valve 10 and line 49 into column 5 to commingle therein and undergoseparation and fractionation with the charging stock, conversionproducts from coil I and reflux condensate from fractionator 40;-

The fractionated vapors which, as aforementioned, consist essentially oflow-boiling gasoline fractions and gases, are removed from the upperportion of fractionator I9 through line H and valve 12, whilefractionated vapors from fractionator 40, which comprise good antiknockgasoline fractions of higher end-boiling point than those removed asvapors from fractionator I9 are removed from fractionator 40 throughline l3 and valve 14 and, although these two different boiling rangegasolines may, within the scope of the invention be separately condensedand recovered as separate products, they are, in the particular casehere illustrated, commingled in line 15 and supplied therefrom tocooling and condensation in condenser I5. The resulting distillate anduncondensed normally gaseous products are directed from condenser '56through line I1 and valve 18 to collection and separation in receiver19. The distillate which collects in this zone comprises the final motorfuel product of the process and is directed from the receiver throughline and valve 8| to storage or to any desired further treatment.

Gases collected in receiver 19 are discharged therefrom, at least inpart, through line 82 and valve 83 to storage or elsewhere, as desired.Preferably, however, a regulated portion of these gases is utilized toassist vaporization in chamber I5 and to accomplish this, provision ismade for supplying gases'from the receiver through line 84 and valve 85into chamber I6 to directly commingle in this zone with the liquidproducts undergoing vaporization therein and assist their vaporizationby the partial pressure effect exerted by the gases.

When additional heat is required to obtainthe desired vaporization inchamber I6, it may be supplied to this zone by heating the gases, in anywell known manner not illustrated, prior to their introduction intochamber I6.

The operating conditions which may be employed to successfully conductthe process of the invention in a system of the character illustratedand above described depend upon the type of charging oil utilized andthe market requirements With respect to the characteristics of theproducts. However, as an example of the-operating conditions which maybeemployed inmost instances, a temperature of the order of 975 to 1200 F.may be employed at the outlet of vaporphase heating coil I, preferablywith a superatmospheric pressure at this point in the system of theorder of 100 pounds, or more, per square inch, the temperature andpressure being correlated to give substantially complete vaporization ofthe products leaving coil 1. Chamber 5 is preferably operated atsubstantially the same or somewhat lower pressure than that utilized atthe outlet of coil I and this pressure may be substantially equalized orreduced in the succeeding fractionating, condensing and collectingequipment. Reforming coil 30 is preferably operated with an outlettemperature of from 925 to 1050" F., or thereabouts, with asuperatmospheric pressure measured at the outlet of the coil of from 200to 1000 pounds, or thereabouts, per square inch. The succeedingseparating chamber 34 is preferably operated at a substantially reducedtemperature and pressure, the latter ranging, for example, from 30 to150 pounds, or thereabouts, per square inch and the reformed productspreferably enter this zone at a temperature of the order of 750 to 875F. The pressure employed in chamber 34 may be substantially equalized orreduced in the succeeding fractionating, condensing and collectingequipment. Distilling chamber I5 is preferably operated at asubstantially reduced pressure relative to the pressure employed incolumn 5 and preferably also lower than the pressure employed in chamber34, the pressure in chamber I6 ranging, for example, from 30 to 100pounds, or thereabouts, per square inch. Relatively mild crackingconditions are preferably employed in coil 61, the temperature'at theoutlet of this zone ranging, for example, from 800 to 900 F. when asuperatmospheric pressure above 150 pounds or thereabouts, per squareinch, is I utilized in this zone, while higher temperatures up to 1050F., or thereabouts, may be utilized with lower pressures. Preferably,the pressure employed at the outlet of this zone is somewhat higher thanthat utilized in column 5 in order to permit introduction of the heatedproducts from coil 61 to chamber 5 without pumping or compressionthereof.

As an example of one specific operation of the process as conducted in asystem such as illustrated and above described, the charging stock is aTexas topped crude of approximately 22 A. P. I. gravity which issupplied, in part, to transfer line 32 leading from reforming coil 30 tochamber 33 and, in part, to column 5. The temperature employed at theoutlet'of coil I is approximately 1100 F. with a pressure at this pointin the system of about '75 pounds per square inch. Substantially thesame pressure is utilized in column 5 and the vaporous stream suppliedfrom the latter zone to fractionator I9 has an end boiling point ofabout 650 F. The condensate supplied from fractionator I9 to coil I hasthe same end-boiling point and contains over of the fractions boilingbetween 400 and 600 F. The overhead vaporous stream removed'fromfractionator I9 has an end-boiling point of approximately 275 F. and thecondensate supplied from fractionator I9 to reforming coil 30 has anend-boiling point of approximately 450 F. and contains over of thefractions boiling above 250 F. The temperature employed at the outlet ofreforming coil 30 is approximately 1000 F. with a superatmosphericpressure at this point in the system of about 300 pounds per squareinch. J The pressure employed in chamber 34 is reduced to approximately90 pounds per square inch and the temperature of the reformed productsentering the latter zone is reduced to approximately 870 F. Fractionatoris also operated at a superatmospheric pressure of approximately 90pounds per square inch and the reflux condensate in this zone is cooledand commingled, in part, with the stream of heated products passing fromcoil I to column 5 and, in part, to the stream of heated productspassing from coil 61 to column 5. The end-boiling point of the overheadvaporous stream removed from fractionator 40 is approximately 400 F.Chamber I6 is operated at a superatmospheric pressure of about 30 poundsper square inch and gases from receiver 19 are supplied to this zone toassist vaporization therein, the receiver being operated at asuperatmospheric pressure of about pounds per square inch. Thetemperature employed at the outlet of coil 61 is approximately 975 F.with a superatmospheric pressure at this point in the system of about100 pounds per square inch.

The above described operation will yield per barrel of charging stockapproximately 51% of 400 F. end-point gasoline which is a blend of thegasolines recovered from the fractionated vaporous stream fromfractionator l9 and the fractionated vaporous stream from fractionator40. Approximately 22% based on the charging stock of liquid residue,having good fuel oil characteristics, is produced and the remainder ofthe charging stock is accountable for as uncondensed gases.

I claim as my invention:

1. A hydrocarbon oil cracking process which comprises reforming a lightcondensate, derived as hereinafter set forth and consisting essentiallyof heavy gasoline fractions, under thermal cracking conditions regulatedto produce therefrom high yields of gasoline of lower initial boilingpoint and improved antiknock value, separating from the products of thereforming operation a fractionated vaporous stream consistingessentially of said improved antiknock gasoline and gas, condensing saidgasoline and separating the same from the uncondensed gases, separatingselected heavier liquid components from the reformed products andcommingling the same with at least a portion of the hydrocarbon oilcharging stock for the process and with other conversion products of theprocess derived as hereinafter set forth, separating the resultingmixture into. a relatively clean vaporous stream and a stream of heavierliquid fractions, substantially vaporizing the latter in a zone ofreduced pressure relative to that at which the last mentioned separationis effected, whereby to form additional vapors and heavier, non-vaporousresidue, separately cracking said additional vapors and comminglingresulting conversion products, as aforesaid, with said selected heavierliquid components of the reformed products, fractionating saidrelatively clean vapors to form a clean condensate substantially devoidof gasoline, a lighter condensate consisting essentially of heavygasoline fractions and comprising the oil subjected to said reforming,and a vaporous stream consisting essentially of gas and good antiknock,light gasoline fractions of lower end boiling point than said gasolinerecovered from the reformed products, condensing said light gasoline andseparating the same from the uncondensed gas, separately cracking saidclean condensate in essentially vaporous state and commingling resultingproducts, as aforesaid, with said selected heavier liquid components ofthe reformed products.

2. The process defined in claim 1 wherein hydrocarbon oil charging stockfor the process is commingled with the reformed products prior to theseparation therefrom of said selected heavier liquid components, wherebyto include at least a portion of said charging oil therein.

3. The process defined in claim 1 wherein hydrocarbon oil charging stockfor the process is commingled with the reformed products prior toseparation of their vaporous and liquid components, and wherein a liquidfraction, heavier than said selected liquid components of the reformedproducts and including heavy fractions of the charging stock, isseparated from the mixture of charging oil and reformed products andsupplied to said zone of reduced pressure vaporization.

4. The process defined in claim 1 wherein a portion of said uncondensedgases is introduced into said zone of reduced pressure vaporization toassist vaporization therein and commingled with said additional vaporssupplied to the second mentioned cracking step.

JEAN DELA'I'TRE SEGUY.

